AN EXPERIMENTAL-CONTROL GROUP DESIGN WITH A 12-MONTH POSTRELEASE FOLLOWUP WAS EMPLOYED TO STUDY 150 INMATES WHO VOLUNTEERED FOR PARTICIPATION IN THE GROUP THERAPY PROGRAM. THE INMATES WERE IN A MINIMUM SECURITY INSTITUTION UNDER THE JURISDICTION OF THE ONTARIO MINISTRY OF CORRECTIONAL SERVICES IN CANADA. PREASSESSMENT AND POSTASSESSMENT MEASURES OF PERSONALITY AND BEHAVIORAL ADJUSTMENT AND MEASURES OF ADJUSTMENT IN PRISON WERE USED, ALONG WITH AN INDIVIDUAL INTERVIEW AND A SEARCH OF OFFICIAL RECORD SOURCES IN THE 12-MONTH FOLLOWUP. EXPERIMENTAL AND CONTROL GROUPS WERE COMPARED ON THREE MEASURES OF ADJUSTMENT TO PRISON REGULATIONS DURING THE STUDY PERIOD: DAYS SERVED IN SOLITARY CONFINEMENT, NUMBER OF CONDUCT POINTS DEDUCTED, AND NUMBER OF MISCONDUCT REPORTS. THE FOCUS OF FOLLOWUP WAS ON EMPLOYMENT, INVOLVEMENT WITH THE LAW, AND THE USE OF ALCOHOL OR OTHER DRUGS SINCE RELEASE AND ON MEASURES OF RECIDIVISM. NO SIGNIFICANT OVERALL DIFFERENCES BETWEEN THE EXPERIMENTAL AND CONTROL GROUPS WERE OBSERVED WITH REGARD TO POSTASSESSMENT PERSONALITY AND BEHAVIORAL FUNCTIONING AND WITH REGARD TO PRISON ADJUSTMENT. A TOTAL OF 128 MEN WERE SUCCESSFULLY CONTACTED AT FOLLOWUP. THERE WERE NO SIGNIFICANT GROUP DIFFERENCES IN EMPLOYMENT OR ARREST HISTORIES, ATTENDANCE AT ALCOHOLICS ANONYMOUS, ALCOHOL CONSUMPTION LEVELS, OR THE USE OF ILLICIT DRUGS. SIMILARLY, THERE WERE NO APPRECIABLE DIFFERENCES BETWEEN THE GROUPS IN TERMS OF RECIDIVISM. THE STUDY FINDINGS DO NOT PROVIDE SUPPORT FOR THE REHABILITATIVE FUNCTION OF GROUPS THERAPY PROGRAMS FOR INMATES WITH ALCOHOL AND DRUG PROBLEMS. SUPPORTING DATA AND REFERENCES ARE INCLUDED. (DEP)